The Valley has experienced three large dust storms in the last
eight weeks, and there's a chance we will see a few more before the
official end of the monsoon on Sept. 30.

The storms, which have reached as high as 1,000 feet and 50
miles wide throughout much of Maricopa and Pinal counties, were
stirred up in open field and desert areas by thunderstorms between
Phoenix and Tucson. They left people in awe as they blanketed
residential areas on July 5, July 18 and most recently, Aug.
19.

The trifecta of storms stirred up winds as high as 60 mph,
causing low visibility driving conditions, power outages to
thousands of SRP and APS customers, and delayed flights at Phoenix
Sky Harbor International Airport.

"I didn't have anything to compare them to," said meteorologist
Charlotte Dewey, who has worked for the National Weather Service in
Phoenix for the last 18 months.

Dewey is from Colorado, where she had never witnessed a dust
storm. "They're fascinating to me. When the thunderstorms
dissipate, the outflow pushes the dust to Phoenix. So, when we do
get some thunderstorms, they produce high winds, and when they
produce downburst winds, it kicks up a lot of dust after dry
conditions."

Weather officials say that such large dust storms only happen in
Africa's Sahara Desert, parts of the Middle East - and in Arizona.
A term that has become more familiar with the large dust storms
this year is "haboob," an Arabic word, meaning "wind."

A haboob is a wall of dust as a result of a microburst or
downburst.

The air forced downward is pushed forward by the front of a
thunderstorm cell, stirring up dust and debris with it, as it
travels across dry areas.

As dry conditions lingered in the Valley the past two weeks with
a heat wave and four record-high temperatures ranging from 112 to
114 degrees, Valley residents saw air quality diminished by the
large storms that left dust lingering in the air for at least two
days, according to Dewey.

Dewey said that with the lack of rain this monsoon, there's a
good chance that there could be more large-scale dust storms in the
upcoming weeks.

"We've seen some large dust storms this season," she said. "It's
not unusual to get four or five in a monsoon season, but to see the
large ones we have is rare."